Missing bushing/clamps

I always call out any wire entering a panel/knockout without a bushing/clamp. I was just watching http://www.nachi.org/inspection-video-electrical-joe-tedesco-2.htm and they stated this is needed only if the wire is 4 awg or larger???

If this is correct why only 4awg or larger???

Thank you

all wires need to be protected against sharp edges .

1 Like

Not sure what you mean by clamp but any raceway with conductors #4 or larger require an insulating bushing. A cable connector such as for SE cable does not require a bushing even for #4 or larger conductors.

Clamps or connectors attach a cable to the enclosure. Bushing are installed over the end of a fitting to provide a smooth surface. They have no means to attach anything to the enclosure. Two items with different functions. Robert provided one code cite. The other is in Article 314.

Thank you all - I found some of the code ref. on this:
NEC 314.17(B)&© **[FONT=Arial,Arial][size=2]The outer jacket of type NM cable shall be secured to the box and extend into the box at least ¼ inch.


[size=3]314.17 Conductors Entering Boxes, Conduit Bodies, or Fittings.


  [/FONT]Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion and shall comply with 314.17(A) through (D). 

I couldn’t find all of the code A - D.
I see circuit branch wires entering metal junction boxes, switches, receptacles and panels without connectors often.
Have a blessed day!